The present invention relates to an apparatus for measuring the density of a single or multiphase stream by utilization of the gamma ray absorption method, the apparatus being of the type in which the single or multiphase stream is conducted through a flow channel and is penetrated or traversed by gamma radiation which is recorded after passage through the stream by one or a plurality of detectors.
In such apparatus, the density of such a stream is determined according to the gamma ray absorption method. The measuring principle is based on the differences in attenuation, or weakening, of the intensity of the gamma radiation during passage through substances having different densities. Thus the intensity of gamma radiation is reduced to a greater degree when the measuring path traverses a flow channel in which only a liquid flows than when it traverses a two-phase liquid-vapor mixture in the flow channel and it is weakened the least when, for example, only vapor is disposed in the measuring path. These differences in weakening of intensity are used as a measure for the amount of vapor, or for the volumetric vapor content, respectively, in the flow channel.
The present invention is primarily concerned with determining the phase distribution states of the type depicted, in longitudinal and axial cross sections, respectively, in FIGS. 1a-1h, which show respective examples of bubble flow in FIG. 1a, varicose flow in FIG. 1b, laminar flow in FIG. 1c, sinuous flow in FIG. 1d, surging flow in FIG. 1e, plugged flow in FIG. 1f, film flow in FIG. 1g and mist flow in FIG. 1h, for the example of a two-phase, gas-liquid stream in a horizontal tube.